Relief-valve for locomotives.



` Nm 657,472. Patented Sept. 4, |900.

S. M. VAUCLMMA RELIEF VALVE FDR LQGQMOIIVES.

(Applimon med .Tuna ao 15990,n

UNITED *STATESa PATENT EEICE.

sAMUELM. vAUcLAIN, oF PHILADELPHIA, PENNSYLVANIA.

RELIEF-VALVE FOR LOCOMOTIVES.

SPECIFICATION forming part of Letters Patent No. 657,472, dated September 4, 1900.

Application filed J' une 30, 1900.

To all whom it may concern.-

Beit known that I, SAMUEL lvLVAUcLAIN, a citizen of the United States, residingin Philadelphia, Pennsylvania, have invented certain Improvements in Relief-Valves for Locomotives, of which the following is a specification.

The object of my invention is to prevent the formation of a partial vacuum in the lowpressure cylinder of a compound engine and the passages leading thereto and to prevent the accumulation of steam in the low-pressure cylinder, due to a leaky throttle. This object I attain by coupling a pipe to the central I chamber of the valve and mounting a reliefvalve in this pipe.

The gure in the accompanying drawing is a sectional view of sufficient of a piston-valve and its chest to illustrate my invention.

In the present instance, A is the cylindrical valve-chamber, having a bushing et.

B is the high-pressure cylinder, and C is the low-pressure cylinder.

E is the central exhaust-port. H represents the ports'leading to the high-pressure cylinder B, one on each side of the central exhaust-port, and L L are the ports leading to the low-pressure cylinder C. These ports are between the high-pressure ports and the steam-ports at the end. It will be understood, however, that in some instances the exhaust-ports may be at the end and steam may enter through a central port.

The piston-valve D has a head d at each end and two rings CZ' between the two heads. Between each head d and a ring d are passages f f,'which form communication at one side with the low or the high pressure ports and on the other side with the high and low pressure ports. The center f' of the valve is hollow, forming communication between the passages ff, so that when the valveis in the position shown in the ligure the steam will pass from the high-pressure port on one side to the low-pressureport on the opposite side. The central annular groove g in the piston between the two rings d d' forms a communication between the exhaust-port and through one of the ports L, leading from the low-pressure cylinder.

When the valve is in the position shown in the drawing, the left-hand end of the high- Serial No. 22,120. (No model.)

pressure cylinder is taking steam through the steam-inlet port S at the left-hand end of the valve-chamber and the left-hand port H and steam is exhausting from the opposite end of said cylinder through the hollow valve to the left-hand port L of the low-pressure cylinder, the opposite end of the low-pressure cylinder exhausting through the channel formed by the groove g in the valve to the exhaust-passage E.

D' is the valve-rod, connected in the ordinary manner to the valve-operating mechanism, and in order to balance the valve I extend from the rear of the valve a tubular stem D2. This stem passes through the packingbox ct in the head of the valve-chest. `The tubular stem D2 extends through the valve D in the present instance and is a continuation of the valve-rod D', although in some instances it may be a stem independent of the valve-rod. I perforate the stem at d2, as shown, and provide a back-pressure reliefvalve I at the end of the stem. In the present instance this valve I rests on a projection t', cast on an elbow D3, screwed into the stem D2. Screwed into the upper portion of the elbow is a valve-seat I, having a central stem t', on which is screwed a cap 2.

When the valve is at rest, the normal position is open, it resting upon the projection as shown in the drawing; but as soon as steam is admitted to the valve the pressure of steam will immediately close the valve against its seat and hold it there during the normal working of the engine.

By my invention the locomotive can drift without creating a vacuum in the low-pressure cylinder or the passages leading thereto, as when steam is cut off the check-valve will open and air will be drawn through"`the hollow stem into the central portion f of the valve-chamber. This construction will prevent locomotives from starting owing to leaky throttles, as the steam as it slowly escapes will pass through the hollow stem D2 and around the valve I.

`I claim as my invention- `1. The combination of the cylinders of a compound engine, a hollow valve controlling the iiow of steam to and from the said cylinders, a hollow stem communicating with the passage in the valve, and a relief-valve in ICO this tubularstem clos-ing against steam-pressure, substantially'asfdescribed 2. 'Ihe combination of the cylinders of a compound engine, a valve-chamber communicating with the'said cylinders,a piston- Valvetherein having acentral 4passage icom- F municating with the ports leading to the ends l of thesaid cylinders, a Ahollow stem extending into the v alve from the rear and iperfo-y rated, said stem vextending" through a packlin'gflox'in fthe valve-casing, anda-valve closing against steam-pressure, said valve being mounted on the stem, substantially as described- 'l i Y l w eLjThe combinationy of a hollow pistonv alve,arste-m kextendingfrom the -rear of said valve, the Vportion of the stem wit-hin the `valvelbeing ,perforated,-l an elbow secured to l'the end of the stem, a valve-seat secured in lsaid elbow, a valve mounted in the elbow and .closing againstthefseatunder steampressure,

Asubstantiallyas described.`

AIn Ktestimonywhereof I have signed my name to this specification in vthe presence of two subscribing witnesses.4 I l SAMUEL VAUCLAIN Vitnesses:

KENNETH RUSHTQN, WILLIAM DE KRAFFf'r. 

